1. Technical Field
The present invention relates to liquid ejecting heads and liquid ejecting apparatuses, and is particularly useful when applied to a laminated structure in which a plurality of components having different coefficients of thermal expansion are attached to one another with attachment surfaces interposed therebetween.
2. Related Art
As a liquid ejecting apparatus, an ink jet recording apparatus (hereinafter, also called “recording apparatus”) that performs printing by ejecting ink (liquid) from an ink jet recording head (hereinafter, also called “recording head”) in accordance with recording data while feeding a recording medium in a paper feed direction is widely known. The recording head pressurizes ink filling a pressure generation chamber by the displacement of a piezoelectric element so as to eject the ink to the exterior through nozzles formed in a nozzle plate.
Among the recording heads according to the past technique as described above, there exits such a recording head that has a plurality of ink jet recording head main bodies held in a holder made of resin, each of the ink jet recording head main bodies being a unit configured to eject ink through a nozzle. In the above-mentioned recording head, the ink jet recording head main bodies and the holder are attached and fixed to a fixing plate with respective end surfaces on a nozzle plate side of the ink jet recording head main bodies and the holder interposed therebetween. Here, the fixing plate is formed of a SUS plate.
As such, a separation can occur in an attachment portion with the fixing plate in some case due to heat generated in a drive unit including a piezoelectric element resulting from driving of the recording head. To be more specific, heat generated in the head main body is transferred to the holder. The holder is significantly deformed by the heat because the holder, which is made of resin, has a large volume and its coefficient of thermal expansion is greater than that of the fixing plate made of SUS. Because of such significant deformation of the holder, a large stress is generated in the attachment portion with the fixing plate. This stress is transmitted from the fixing plate to the head main body through the attachment portion of the fixing plate and the head main body. As a result, there is a case where a separation occurs in the attachment portion of the holder and the fixing plate, the attachment portion of the head main body and the fixing plate, or the like. In addition, the stress that acts upon the head main body via the attachment portion causes deformation of the nozzle plate in some case. In the case where the nozzle plate is deformed, quality of printing carried out using ink that is ejected through the nozzle will be degraded.
The above problem occurs not only in ink ejecting recording apparatuses configured to eject ink, but also occurs likewise in liquid ejecting apparatuses configured to eject liquids other than ink.
Techniques disclosed in JP-A-2014-4692, JPA-2005-225147, and JP-A-2008-265191, respectively, are known as the existing techniques aimed at the prevention of deformation caused by thermal expansion in the recording head configured as described above. In JP-A-2014-4692, a member having a groove to absorb thermal expansion of an actuator substrate is provided between the actuator substrate and a nozzle plate. However, a hollow bellows structure is not disclosed therein. In JP-A-2005-225147, at a bonding interface where different substrates are bonded, a groove is provided in one of the substrates so as to follow a warp caused by thermal expansion, whereby bonding-layer separation is prevented. However, deformation caused by thermal expansion is not absorbed. In JP-A-2008-265191, a bellows portion that absorbs thermal expansion and is capable of free movement is provided between a head and a head support member. However, deformation caused by thermal loads generated in constituent members that are fixed to both ends of the bellows portion is not absorbed.